Lung cancer accounted for almost one third of cancer deaths in the United States in 2005, and is broadly classified into two types: non-small cell lung cancer and small cell lung cancer. Non-small cell lung cancer (NSCLC) comprises 80-85% of lung cancer cases in the United States. The types of NSCLC are named for the kinds of cells found in the cancer and how the cells look under a microscope. NSCLC comprises three major types: (i) Squamous cell carcinoma, which begins in squamous cells, that are thin, flat cells that look like fish scales. Squamous cell carcinoma is also called epidermoid carcinoma; (ii) Large cell carcinoma, which begins in several types of large lung cells; (iii) Adenocarcinoma, which begins in the cells that line the alveoli of the lung and make substances such as mucus. Other less common types of NSCLC include pleomorphic carcinoma, carcinoid tumor and unclassified carcinoma.
Diagnosis of NSCLC is done by a pathologist's examination of suspected tissue, such as a biopsy sample. After NSCLC diagnosis, the patient's disease is assigned a prognosis (the chance of recovery) using the patient's overall health and age, the severity of symptoms such as coughing and difficulty in breathing, the particular type of NSCLC, and the staging of the cancer. Staging takes into account the size of the tumor and whether the tumor is present in the lung only or has spread to other places in the body. The particular treatment options for a NSCLC patient are then selected based upon these considerations, and the cancer staging is an important component for treatment selection. Patients with early stage NSCLC can be potentially be cured by surgical resection to remove the tumor, but the current diagnostic modalities are not able to predict which patients will recur after surgery.
Two or more separate tumor nodules are present in the same lobe; or (iii) a malignant pleural effusion is present, which is the existence of fluid containing cancer cells in the space surrounding the lung.
The N category depends on which, if any, of the lymph nodes near the lungs are affected by the cancer. In the NO category, the cancer has not spread to any lymph node. In the N1 category, the cancer has spread to lymph nodes within the lung or into the hilar lymph nodes (those located around the area where the bronchus enters the lung). In N1 category the affected lymph nodes are only on the same side as the cancerous lung. In the N2 category, the cancer has spread to subcarinal lymph nodes (those which are around the point where the trachea branches into the left and right bronchi) or to lymph nodes in the mediastinum (the space behind the chest bone and in front of the heart). In the N2 category, the affected lymph nodes are on the same side of the cancerous lung. In the N3 category, the cancer has spread to lymph nodes near the collarbone on either side, and/or to the hilar or mediastinal lymph nodes on the side opposite the cancerous lung.
The M category depends on whether the cancer has metastasized and spread to any distant tissues and organs. In the M0 category, there is no distant cancer spread. In the M1 category, the cancer has spread to 1 or more distant sites. Sites which are considered distant include other lobes of the lungs, lymph nodes further than those used to determine the N category of the cancer, and other organs or tissues such as the liver, bones, or brain.
Once the T, N, and M categories have been assigned for the particular NSCLC, this information is combined (stage grouping) to assign an overall stage of 0, I, II, III, or IV (see Table 1). Various combinations of the T and N categories are combined into stages. The stages identify tumor types that have a similar prognosis and are treated in a similar way. As noted in Table 1, a tumor with distant spread (i.e. an M1 category cancer) is considered Stage IV, regardless of tumor size of involvement of lymph nodes. The following Table from the NCCN internet web site shows the combined category and stage classification for NSCLC.
TABLE 1Overall StageT CategoryN CategoryM CategoryStage 0TisN0M0Stage IAT1N0M0Stage IBT2N0M0Stage IIAT1N1M0Stage IIBT2N1M0T3N0M0Stage IIIAT1N2M0T2N2M0T3N1M0T3N2M0Stage IIIBAny TN3M0T4Any NM0Stage IVAny TAny NM1
NSCLC patients with lower stage numbers generally have a more favorable prognosis and outlook for survival, and these patients are generally treated by surgical resection of the tumor. However, even for early stage patients, such as those with Stage 1B, Stage IIA or IIB NSCLC, a significant percentage of these patients will recur after surgical resection with more aggressive disease and die. The current clinical diagnostic methods are incapable of identifying early stage NSCLC prognosis with sufficient accuracy to direct more aggressive therapy against those patients more likely to recur. Better in vitro diagnostic methods to identify higher risk, early stage NSCLC patients who should receive neoadjuvant or adjuvant chemotherapy or even forgo surgical resection altogether, are therefore needed.
Molecular in vitro diagnostic assays based on fluorescence in situ hybridization (FISH) using fluorescently labeled DNA hybridization probes to identify chromosomal abnormalities have been disclosed for use in the selection of chemotherapy for NSCLC patients, see PCT/US2005/018879, “Methods for prediction of clinical outcome to epidermal growth factor inhibitors by cancer patients”, M. Garcia et al. FISH assays have also been used as an initial diagnostic assay for NSCLC, see U.S. Patent Application 20060063194, “Methods and probes for the detection of cancer”, L. Morrison et al., published Mar. 23, 2006 (hereafter referred to as “Morrison '194”), which is incorporated herein by reference in its entirety. The Morrison '194 application describes multiple FISH probe sets useful for screening and diagnosis of NSCLC, and one probe set described in Morrison '194 is commercially available as the LAVysion™ probe set from Abbott Molecular, Inc. (Des Plaines, Ill., U.S.A.) under ASR (Analyte Specific Reagent) labeling for use by clinical laboratories to produce clinical diagnostic assays. Under the U.S. Food and Drug Administration ASR labeling requirements, the ASR labeling must not include any claims as to the medical utility of the ASR. The LAVysion ASR probe set comprises four FISH probes: a chromosome 5p15 locus specific probe labeled with the SpectrumGreen green fluorophore, a chromosome 8q24 locus specific probe labeled with the SpectrumGold yellow fluorophore, a chromosome 6 enumeration probe labeled with the SpectrumAqua blue fluorophore, and a chromosome 7p12 locus specific probe labeled with the SpectrumRed red fluorophore.
Multiple research publications describe research performed using the LAVysion probe set, see e.g., M. Garcia et al., “Multi-target interphase fluorescence in situ hybridization assay increases sensitivity of sputum cytology as a predictor of lung cancer”, Cancer Detection and Prevention, Vol. 24, Issue 4, 2004: 244-251; K. Halling et al., “A Comparison of Cytology and Fluorescence in Situ Hybridization for the Detection of Lung Cancer in Bronchoscopic Specimens”, Chest, 2006; 130:694-701; and I. Zudaire et al., “Molecular characterization of small peripheral lung tumors based on the analysis of fine needle aspirates”, Histol. Histophathol. (2008) 23: 33-40. See also the review article K. Hailing et al., “Fluoresence in situ hybridization in diagnostic cytology”, Hum. Path. (2007) 38: 1137-11444. None of these previous patent applications or publications on FISH assays for NSCLC have disclosed the use of FISH probes to more accurately identify prognosis for early stage NSCLC, in particular, those classified as Stage IB or Stage II.